C4 AL4 high oil pressure after EV replacement

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Michael_d
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Joined: 05 Jun 2020, 00:09

C4 AL4 high oil pressure after EV replacement

Unread post by Michael_d »

Hi guys, let me start from assuring you that I did search forum for an answer, however, couldn't find my problem anywhere.

So a couple of months ago I started getting service along with gearbox faulty message and rough gear shifts. Upon scanning with Diagbox it turned out to be P0006: pressure regulation variation/recommendation fault, this and other forums suggested notorious electrovalves problem. Replaced them a week ago, dismantled and cleaned the valve block (didn't touch any of the sequential valves though), and if anything it made things worse and rendered car completely undrivable. When changing gears parked there is distinct noise along with noticeable jerk when putting drive gear. When I tried to go for a test drive within a couple of seconds there was a loud thud and box went into limp mode.

I monitored variables through Diagbox and this is what I found (see graphs below):
  • Oil pressure starts from 11.2 bars and the gradually falls as the oil heats up
  • Pressure almost doesn't change when putting into different gears
  • Whenever there is any load on engine pressure instantly goes to 11.2bars regardless of a gear
Oil pressure under load
Oil pressure under load
Because of this as soon as I try to drive gearbox goes straight into limp mode with error P1167 Pressure regulation fault (difference / reference value)

I ruled out the possibility of broke oil pressure sensor since I can see that voltage follows the pressure and from what I've read in case of a defected one pressure is constant.
pressure sensor voltage
pressure sensor voltage
I repeated the oil levelling procedure to make sure it's not the fault of me overfilling the oil, sadly no change. On a side note, I put 4 litters of a new ATF LT71141 oil and got 5 litres out, is it normal?
Another thing is that I noticed that on old fault reads main pressure regulation valve status says activated whereas now is deactivated. Does it mean that electrovalve is broken?
Faults before and after EV replacement
Faults before and after EV replacement
Both old and new EVs were of the Borg Warner type. It's 2006 C4 mk I 1.6.
I will highly appreciate any suggestions from you. I'm helpless at the moment, no idea what I can do more to fix it.

I attach more graphs that capture oil pressure over time as the oil temperature increases.
  • Cold oil
Spoiler: show
Cold oil
Cold oil
  • Warming up, circa 35 degrees
Spoiler: show
Warming up, circa 35 degrees
Warming up, circa 35 degrees
  • Reaching operating temperature
Reaching operating temperature
Reaching operating temperature
  • Warmed up
Spoiler: show
Warmed up
Warmed up

wheeler
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Re: C4 AL4 high oil pressure after EV replacement

Unread post by wheeler »

Did you follow the oil level check to the letter?
The oil being at the correct temperature when checking the level is critical. When it’s warming up you only have a very short time window to do the level check. Did you add a half litre of fluid then pull the level plug? You should get a stream of oil followed by drips, if you only get drips you need to ad another half litre.

Michael_d
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Joined: 05 Jun 2020, 00:09

Re: C4 AL4 high oil pressure after EV replacement

Unread post by Michael_d »

Hi wheeler, yes I did. Followed instruction from this thread and watched dozens of YT videos beforehand. Also, tracked oil temperature with lexia so I'm 100% sure that I did it right both times.

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GiveMeABreak
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Re: C4 AL4 high oil pressure after EV replacement

Unread post by GiveMeABreak »

Did you reinitialise the oil counter with Lexia or suitable diagnostic tool as per the procedure?

As for the electrovalves replacement - I put a guide up here too for reference:

viewtopic.php?p=629448#p629448

Michael_d
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Joined: 05 Jun 2020, 00:09

Re: C4 AL4 high oil pressure after EV replacement

Unread post by Michael_d »

Hi Marc, thank you for the guide, it's very clear and instructive. In fact, I used it as my primary reference along with other YT videos. When I tried to adjust the oil wear counter in Diagbox I got "operating conditions not satisfied" error. The counter is currently at 12000 so I thought that I can ignore it for the time being.
Thanks.

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GiveMeABreak
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Re: C4 AL4 high oil pressure after EV replacement

Unread post by GiveMeABreak »

It won't be happy as it changes it's operating mode / parameters as the oil gets older and needs to be reset back to zero when it's been replaced. I've not heard of that message before - perhaps it didn't like the value you were trying to input?

Michael_d
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Joined: 05 Jun 2020, 00:09

Re: C4 AL4 high oil pressure after EV replacement

Unread post by Michael_d »

I finally managed to adjust the counter, the diagbox update resolved the issue. Sadly, it hasn't altered the gearbox behaviour in any way. The symptoms are exactly the same - high pressure 11.25 and strong jerk with noise when putting selector into drive.